U.S. patent number 10,578,006 [Application Number 15/772,816] was granted by the patent office on 2020-03-03 for method for controlling a mechanically controllable coolant pump for an internal combustion engine.
This patent grant is currently assigned to PIERBURG GMBH. The grantee listed for this patent is PIERBURG GMBH. Invention is credited to Michael-Thomas Benra, Andreas Burger, Stefan Rothgang, Stephan Zielberg.
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United States Patent |
10,578,006 |
Zielberg , et al. |
March 3, 2020 |
Method for controlling a mechanically controllable coolant pump for
an internal combustion engine
Abstract
A method for controlling a coolant pump for an engine includes
delivering a coolant via a coolant pump impeller into a delivery
duct to a pump outlet, and adjusting the delivery based on a
position of an adjustable control slide which controls a
throughflow cross-section of an annular gap between the coolant
pump impeller outlet and the delivery duct. A first pressure
chamber on a side of the control slide is filled with a pressurized
coolant to decrease the throughflow cross-section and the coolant
volume flow delivered to the pump outlet, or a second pressure
space arranged on an opposite side is filled with the pressurized
coolant to increase the throughflow cross-section and the coolant
volume flow delivered to the pump outlet. The control slide is
moved into a defined position when the engine is switched off
dependent on a coolant temperature and remains in that position
until a restart.
Inventors: |
Zielberg; Stephan (Bochum,
DE), Burger; Andreas (Krefeld, DE), Benra;
Michael-Thomas (Castrop-Rauxel, DE), Rothgang;
Stefan (Rheinberg, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
PIERBURG GMBH |
Neuss |
N/A |
DE |
|
|
Assignee: |
PIERBURG GMBH (Neuss,
DE)
|
Family
ID: |
57206228 |
Appl.
No.: |
15/772,816 |
Filed: |
October 19, 2016 |
PCT
Filed: |
October 19, 2016 |
PCT No.: |
PCT/EP2016/075081 |
371(c)(1),(2),(4) Date: |
May 02, 2018 |
PCT
Pub. No.: |
WO2017/076648 |
PCT
Pub. Date: |
May 11, 2017 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180313251 A1 |
Nov 1, 2018 |
|
Foreign Application Priority Data
|
|
|
|
|
Nov 6, 2015 [DE] |
|
|
10 2015 119 092 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01P
7/16 (20130101); F04D 15/0038 (20130101); F01P
2007/146 (20130101); F01P 2023/08 (20130101); F01P
2037/02 (20130101) |
Current International
Class: |
F01P
7/00 (20060101); F01P 7/16 (20060101); F04D
15/00 (20060101); F01P 7/14 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102149923 |
|
Aug 2011 |
|
CN |
|
103459854 |
|
Dec 2013 |
|
CN |
|
103764968 |
|
Apr 2014 |
|
CN |
|
203516133 |
|
Apr 2014 |
|
CN |
|
10 2008 026 218 |
|
Dec 2009 |
|
DE |
|
10 2011 079 898 |
|
Jan 2013 |
|
DE |
|
10 2012 207 387 |
|
Jan 2013 |
|
DE |
|
10 2013 018 205 |
|
Jun 2014 |
|
DE |
|
2004-108343 |
|
Apr 2004 |
|
JP |
|
WO 2012/119622 |
|
Sep 2012 |
|
WO |
|
Primary Examiner: Wongwian; Phutthiwat
Assistant Examiner: Manley; Sherman D
Attorney, Agent or Firm: Thot; Norman B.
Claims
What is claimed is:
1. A method for controlling a coolant pump which is configured to
be mechanically controllable for an internal combustion engine, the
method comprising: delivering a coolant via a coolant pump impeller
into a delivery duct which surrounds the coolant pump impeller to a
pump outlet; adjusting the delivery based on a position of a
control slide, wherein the control slide is configured to be
adjustable so as to control a throughflow cross-section of an
annular gap arranged between an outlet of the coolant pump impeller
and the delivery duct; filling a first pressure chamber arranged on
a first side of the control slide with a pressurized coolant to
decrease the throughflow cross-section and to thereby decrease the
coolant volume flow delivered to the pump outlet, or filling a
second pressure space arranged on a second side of the control
slide which is axially opposite to the first side with the
pressurized coolant to increase the throughflow cross-section and
to thereby increase the coolant volume flow delivered to the pump
outlet; and moving the control slide into a defined position during
a switch-off of the internal combustion engine dependent on a
coolant temperature, wherein the control slide remains in the
defined position until the internal combustion engine is
started.
2. The method as recited in claim 1, wherein, during the switch-off
of the internal combustion engine, the method further comprises:
moving the control slide into a first position to close the annular
gap when the coolant temperature falls below a defined threshold
value.
3. The method as recited in claim 2, wherein, during the switch-off
of the internal combustion engine, the method further comprises:
moving the control slide into a second position to fully open the
annular gap when the coolant temperature corresponds to the defined
threshold value or exceeds the defined threshold value.
4. The method as recited in claim 3, wherein the opening of the
annular gap is performed by providing a progressive pressure
increase in the second pressure chamber.
5. The method as recited in claim 3, wherein the defined threshold
value for the coolant temperature is provided as a function of the
ambient temperature and is saved in a characteristic map.
6. The method as recited in claim 3, wherein the defined threshold
value corresponds to a desired value for an operating temperature
of the coolant during operation as defined in an engine
control.
7. The method as recited in claim 3, wherein, depending on a
position of a 3/2-way electromagnetic valve, the pressurized
coolant is fed to the first pressure chamber or to the second
pressure chamber, and the method further comprises: driving the
3/2-way electromagnetic valve during the switch-off of the internal
combustion engine to move the control slide into the first position
or into the second position.
8. The method as recited in claim 1, wherein, during the switch-off
of the internal combustion engine, the method further comprises:
performing a control via a cut-off of an ignition of the internal
combustion engine.
9. The method as recited in claim 8, further comprising: moving the
control slide into a position to close the annular gap during the
cut-off of the ignition of the internal combustion engine.
10. The method as recited in claim 8, wherein, the control is
performed in a start-stop operation.
11. The method as recited in claim 8, wherein the control is
performed in a coasting mode of a vehicle.
Description
CROSS REFERENCE TO PRIOR APPLICATIONS
This application is a U.S. National Phase application under 35
U.S.C. .sctn. 371 of International Application No.
PCT/EP2016/075081, filed on Oct. 19, 2016 and which claims benefit
to German Patent Application No. 10 2015 119 092.3, filed on Nov.
6, 2015. The International Application was published in German on
May 11, 2017 as WO 2017/076648 A1 under PCT Article 21(2).
FIELD
The present invention relates to a method for controlling a
mechanically controllable coolant pump for an internal combustion
engine, where a coolant is delivered via a coolant pump impeller
into a delivery duct surrounding the coolant pump impeller and to a
pump outlet, wherein the delivery depends on the position of an
adjustable control slide via which a throughflow cross-section of
an annular gap between an outlet of the coolant pump impeller and
the surrounding delivery duct is controlled, and wherein for
reduction of the coolant volume flow delivered to the pump outlet
by decreasing the throughflow cross-section a first pressure
chamber on a first axial side of the control slide is filled with a
pressurized coolant.
BACKGROUND
Coolant pumps in internal combustion engines serve to control the
flow of the delivered coolant to prevent the internal combustion
engine from overheating. These pumps are in most cases driven via a
belt or a chain drive so that the coolant pump impeller is driven
at the speed of the crankshaft or at a fixed ratio to the speed of
the crankshaft.
In modern internal combustion engines, the delivered coolant flow
must be matched with the coolant demand of the internal combustion
engine or the motor vehicle. The cold running phase of the engine
should in particular be reduced to prevent increased pollutant
emissions and to reduce fuel consumption. This is realized, inter
alia, by restricting or completely switching off the coolant flow
during this phase.
Various pump designs for controlling coolant flow rate are known.
Besides electrically driven coolant pumps, pumps are known which
can be coupled to or decoupled from their drive units via
couplings, in particular hydrodynamic couplings. A particularly
inexpensive and simple manner of controlling the delivered coolant
flow is the use of an axially movable control slide which is pushed
across the coolant pump impeller so that, for reducing the coolant
flow, the pump does not deliver into the surrounding delivery duct
but against the closed slide.
The control of this slide is also performed in different ways.
Besides a purely electric adjustment, a hydraulic adjustment of the
slides has in particular proved successful. A hydraulic adjustment
is in most cases carried out via an annular piston chamber which is
filled with a hydraulic fluid and whose piston is connected to the
slide so that, during filling of the chamber, the slide is moved
across the impeller. The slide is returned by opening the piston
chamber towards an outlet, in most cases via a magnetic valve as
well as by a spring action providing the force for returning the
slide.
For the coolant flow required for moving the slide not to be
supplied via additional delivery units, such as additional
piston/cylinder units, or for other hydraulic fluids not to be
compressed for operating purposes, mechanically controllable
coolant pumps are known on whose drive shaft a second delivery
wheel is arranged via which the pressure for adjusting the slide is
provided. These pumps are designed, for example, as side channel
pumps or as servo pumps.
A coolant pump having a side channel pump acting as a secondary
pump is described in DE 10 2012 207 387 A1. In this pump, via a
3/2-way valve, in a first position, a discharge side of the
secondary pump is closed and a suction side of the pump is
connected to the coolant circuit and the slide, and in a second
position, the discharge side is connected to the slide and the
suction side is connected to the coolant circuit. A spring is used
to return the slide, which spring may be omitted when the pump is
to be reset by the negative pressure produced at the suction
connection.
It is, however, problematic that a sufficient coolant pressure
initially does not exist when starting the internal combustion
engine, via which the control slide is rapidly moved into its
position for closing the duct and thus stopping a coolant flow. A
rapid control of the coolant flow is thus not possible directly
after the start, in particular at an idle speed, so that the
heating times cannot be considerably reduced as in the case of an
immediate switch-off by moving the control slide into the annular
gap.
For vehicles having an automatic start-stop system, several
documents therefore suggest a solution wherein, in addition to a
mechanically driven pump, an electric pump is arranged in the
coolant circuit to maintain the delivery of the coolant at high
coolant temperatures even at low speeds. Such an arrangement is
described, for example, in WO 2012/119622 A2. In the therein
described cooling system, the control slide is to be moved into its
position for closing the duct to prevent an undesired cooling
during the start. This is, however, only possible in the case of
electrically operated actuators since a sufficient hydraulic
pressure to move the control slide is normally not provided at idle
speed.
SUMMARY
An aspect of the present invention is to provide a method for
controlling a mechanically controllable coolant pump for an
internal combustion engine wherein, with a single coolant pump,
both a rapid undelayed heating of the internal combustion engine
and a sufficient coolant flow for preventing overheating can be
provided.
In an embodiment, the present invention provides a method for
controlling a mechanically controllable coolant pump for an
internal combustion engine. The method includes delivering a
coolant via a coolant pump impeller into a delivery duct which
surrounds the coolant pump impeller to a pump outlet, and adjusting
the delivery based on a position of a control slide, wherein the
control slide is configured to be adjustable so as to control a
throughflow cross-section of an annular gap arranged between an
outlet of the coolant pump impeller and the delivery duct. A first
pressure chamber arranged on a first side of the control slide is
filled with a pressurized coolant to decrease the throughflow
cross-section and to thereby decrease the coolant volume flow
delivered to the pump outlet, or a second pressure space arranged
on a second side of the control slide which is axially opposite to
the first side is filled with the pressurized coolant to increase
the throughflow cross-section and to thereby increase the coolant
volume flow delivered to the pump outlet. The control slide is
moved into a defined position during a switch-off of the internal
combustion engine dependent on a coolant temperature, wherein the
control slide remains in the defined position until the internal
combustion engine is started.
BRIEF DESCRIPTION OF THE DRAWING
The present invention is described in greater detail below on the
basis of embodiments and of the drawing in which:
FIG. 1 shows a cross-sectional side view of a coolant pump
according to the present invention.
DETAILED DESCRIPTION
An expected required coolant flow can be adjusted in advance
depending on a respective operating condition, which coolant flow
is immediately effective during the start, since for increasing the
coolant flow delivered to the pump outlet by increasing the
throughflow cross-section pressurized coolant is filled into a
second pressure chamber on a side of the control slide axially
opposite to the first side, and during switch-off of the internal
combustion engine, the control slide is moved into a defined
position depending on the coolant temperature in which the control
slide remains until the engine is started. This is performed by the
purely hydraulic operation of the control slide upon which no
permanently effective forces, such as spring forces, act. The
control slide accordingly always remains in the position selected
during switch-off until the next engine start.
In an embodiment of the present invention, the control slide can,
for example, be moved into a position for closing the annular gap
during switch-off of the internal combustion engine when the
coolant temperature falls below a defined threshold value. During a
start of the internal combustion engine, no coolant flow is
therefore present, which results in a rapid heating. This position
also provides that, during the standstill phase, no coolant flow
is, for example, produced by the thermosiphon effect which would
lead to a further cooling of the internal combustion engine during
a later period of the cold start phase.
It is also advantageous when the control slide is moved into a
position for completely opening the annular gap during switch-off
of the internal combustion engine when the coolant temperature
corresponds to the defined threshold value or exceeds the defined
threshold value. Due to this control, no overheating can occur
during a new start since a sufficient coolant flow is available
even at idle speed because the coolant pump is capable of
delivering freely and an additional cooling of the engine is
provided by the thermosiphon effect during standstill.
The threshold value can, for example, correspond to a desired value
defined in an engine control for the operating temperature of the
coolant during operation of the internal combustion engine. This is
thus the value to which the coolant is to be set by the engine
control during operation of the vehicle to provide a good
lubrication and to prevent overheating. Such a threshold value
would be approximately 95.degree. C., for example, in a normal
motor vehicle.
In an embodiment of the present invention, during a switch-off of
the internal combustion engine, the control can, for example, be
performed by cutting off the ignition of the internal combustion
engine. An optimum coolant flow for the next start can accordingly
be preset during cut-off of the vehicle.
Besides the control methods described, it would also be
advantageous in this state to move the control slide into a
position to close the annular gap independently of the prevailing
coolant temperature during a cut-off of the ignition of the
internal combustion engine. The driver in this state normally
leaves the vehicle for a short or a long period of time so that,
due to the long standstill of the vehicle, a sufficient cooling
takes place. This is in particular the case when a low ambient
temperatures prevail. This would then be preset for the cold start
during a new start of the vehicle so that the heating phase would
be shortened.
It is also advantageous when the control is performed when
switching-off the internal combustion engine during the automatic
start-stop operation. During a stop, the control slide is
accordingly moved into a position in which an overheating or an
undesired cooling is prevented by opening or closing the slide
according to the temperature during the stop.
A similar control can, for example, be performed in a coasting mode
of the vehicle during which the internal combustion engine is
switched off and, accordingly, does not generate any combustion
heat. An undesired cooling or heating in this state depending on
the operating temperature can also be prevented.
In an embodiment of the present invention, the opening of the
annular gap can, for example, also be performed by a progressive
pressure increase in the second pressure chamber. This progressive
pressure increase leads to a slow and continuous opening of the
control slide, whereby a sudden surge of cold water is prevented
which could result in an abrupt cooling of the crankcase.
In an embodiment of the method of the present invention, the
threshold value for the coolant temperature as a function of the
ambient temperature can, for example, be saved in a characteristic
map. For lower ambient temperatures, the threshold value can
accordingly be set to a higher value since a considerable cooling
during a cut-off of the internal combustion engine takes place
without any thermosiphon effect.
The desired control is carried out in a particularly simple manner
when, depending on the position of a 3/2-way electromagnetic valve,
the pressurized coolant is fed to one of the pressure chambers and
the 3/2-way electromagnetic valve is driven during the switch-off
of the internal combustion engine to move the control slide into
the required position. A short signal during cut-off can thus cause
the control slide to be rapidly moved into the desired
position.
A method for controlling a mechanically controllable coolant pump
for an internal combustion engine is thus provided, wherein,
already during a cut-off of the engine, the control slide is preset
with regard to an optimum new start, whereby overheating is
prevented by providing a sufficient coolant flow and a too rapid
cooling of the internal combustion engine is prevented. During the
start, the control slide is also in the optimum position for
shortening the warm-up phases.
The method of the present invention is described below on the basis
of a suitable coolant pump for an internal combustion engine as
shown in the drawing.
The illustrated coolant pump is composed of an outer housing 10 in
which a spiral delivery duct 12 is formed into which a coolant is
sucked via an axial pump inlet 14 that is also formed in the outer
housing 10, which coolant is delivered via the delivery duct 12 to
a tangential pump outlet 16 formed in the outer housing 10 and into
a cooling circuit of the internal combustion engine.
For this purpose, radially inside the delivery duct 12, a coolant
pump impeller 20 is fastened to a drive shaft 18, which coolant
pump impeller 20 is configured as a radial pump wheel, the rotation
of which effects the delivery of the coolant in the delivery duct
12. On the side of the coolant pump impeller 20 axially opposite to
the pump inlet 14, a control pump impeller 22 is formed which is
rotated together with the coolant pump impeller 20. The control
pump impeller 22 comprises blades 24 which are arranged axially
opposite to a flow duct 26 configured as a side channel formed in a
first inner housing part 28. In the first inner housing part 28, an
inlet (not shown in the drawing) and an outlet 30 are formed so
that the control pump impeller 22 together with the flow duct 26
forms a control pump 32 via which the pressure of the coolant is
increased from the inlet to the outlet 30.
The coolant pump impeller 20 and the control pump impeller 22 are
driven via a belt 34 which engages with a belt pulley 36 that is
fastened to the axial end of the drive shaft 18 opposite to the
coolant pump impeller 20. Driving via a chain drive is also
possible. The belt pulley 36 is supported on second housing part 40
via a two-row ball bearing 38. The second housing part 40 comprises
an inner axial through-going opening 42 into which an annular
projection 44 of the first inner housing part 28 projects, via
which the first inner housing part 28 is fastened to the second
housing part 40. The second housing part 40 is fastened to the
outer housing 10 using a seal 46 as an intermediate layer. For this
purpose, the outer housing 10 comprises an accommodation opening 48
at its axial end opposite to the pump inlet 14, into which an
annular projection 50 of the second housing part 40 projects.
The annular projection 50 at the same time serves as a rear stopper
52 for a control slide 54 whose cylindrical circumferential wall 56
can be pushed across the coolant pump impeller 20 so that a free
cross-section of an annular gap 58 between an outlet 60 of the
coolant pump impeller 20 and the delivery duct 12 is controlled.
The coolant flow delivered through the coolant circuit is thus
controlled depending on the position of the control slide 54.
Besides the cylindrical circumferential wall 56, the control slide
54 comprises a bottom 62 having an inner opening 64 from whose
outer circumference the cylindrical circumferential wall 56 axially
extends through an annular gap 66 between the first inner housing
part 28 and the outer housing 10 towards the axially adjoining
annular gap 58. A respective piston ring 68 is arranged in a radial
groove at the inner circumference and at the outer circumference of
the bottom 62 via which piston rings 68 the control slide 54 is
slidingly supported in the radially inner area on the first inner
housing part 28 and in the radially outer area in the annular
projection 50 of the second housing part 40.
On the side of the control slide 54 facing away from the coolant
pump impeller 20, a first pressure chamber 70 is located which is
axially delimited by the second housing part 40 and the bottom 62
of the control slide 54, which is delimited radially outwards by
the outer housing 10 and/or the annular projection 50 of the second
housing part 40, and which is delimited radially inwards by the
first housing part 28. On the side of the bottom 62 facing the
coolant pump impeller 20, a second pressure chamber 72 is formed
which is axially delimited by the bottom 62 and the first housing
part 28, which is delimited radially outwards by the cylindrical
circumferential wall 56 of the control slide 54, and which is
delimited radially inwards by the first inner housing part 28. The
cylindrical circumferential wall 56 of the control slide 54 is
pushed into the annular gap 58 or is removed from the annular gap
58 Depending on the pressure difference prevailing at the bottom 62
of the control slide 54 in the first pressure chamber 70 and in the
second pressure chamber 72.
The pressure difference required for this purpose is generated by
the control pump 32 and is supplied to the respective first
pressure chamber 70 and second pressure chamber 72 by a valve 74
configured as a 3/2-way magnetic valve. For this purpose, an
accommodation opening 76 for the valve 74 is formed in the second
housing part 40, via which valve 74 a throughflow cross-section 80
of a pressure duct 82 is controlled depending on the position of
its closing body 78. The pressure duct 82 extends from the outlet
30 of the flow duct 26 of the control pump 32 up to the first
pressure chamber 70. The second pressure chamber 72 is connected to
the flow duct 26 via a connecting duct which is formed in the first
inner housing part 28, wherein this connecting duct is configured
as a bore which extends from an area of the inlet of the flow duct
26 directly into the second pressure chamber 72. A third flow
connection (not shown in the drawing) of the control valve leads
directly to the suction side of the coolant pump.
If the coolant pump is to deliver a maximum coolant flow during
operation, the annular gap 58 at the outlet 60 of the coolant pump
impeller 20 is completely opened by not applying current to the
magnetic valve 74, whereby, via a spring force, the closing body 78
is moved into a position in which it closes the throughflow
cross-section 80 of the pressure duct 82. As a result, no pressure
is built up by the coolant in the first pressure chamber 70, but
the coolant present in the first pressure chamber 70 can flow off
to the pump inlet 14 of the coolant pump via the other flow
connection (not shown in the drawing) of the magnetic valve 74
which is open in this state. In this state, the control pump 32
instead delivers against the closed throughflow cross-section 80,
whereby an increased pressure builds up in the overall flow duct
26, which also acts in the area of the inlet of the control pump
32, and, accordingly, also builds up in the second pressure chamber
72 via the connecting duct. This increased pressure in the second
pressure chamber 72 results in a pressure difference at the bottom
62 of the control slide 54, which leads to the control slide 54
being moved into a position in which the annular gap 58 is opened
and thus a maximum delivery of the coolant pump is provided.
If the engine control requires a reduced coolant flow to the
cooling circuit, as is the case, for example, during the warm-up
phase of the internal combustion engine after a cold start, current
is applied to the magnetic valve 74, whereby the closing body 78
opens the throughflow cross-section 80 of the pressure duct 82. The
pressure produced at the outlet of the control pump 32 is
accordingly also generated in the pressure duct 82 and in the first
pressure chamber 70, while at the same time the pressure in the
second pressure chamber 72 decreases since a reduced pressure
occurs in the area of the inlet due to the intake of the coolant.
The coolant present in the second pressure chamber 72 is initially
also extracted. In this state, a pressure difference is accordingly
again present at the bottom 62 of the control slide 54, which
pressure difference results in the control slide 54 being moved
into the annular gap 58 and thus the coolant flow in the cooling
circuit being interrupted.
If a magnetic valve 74 configured as a proportional valve or as a
clocked valve having a variable duty ratio is used, it is also
possible to move the valve 74 into intermediate positions, whereby
an equilibrium of forces is attainable for each position of the
control slide 54 so that a complete control of the throughflow
cross-section of the annular gap 58 is provided.
No spring force is accordingly used to adjust the control slide 54.
The control slide 54 of this coolant pump, during a cut-off of the
internal combustion engine and the resultant standstill of both the
coolant pump impeller 20 and the control pump impeller 22, instead
remains in the respective position which it has assumed at the time
of cut-off since a pressure in a pressure chamber can merely be
decreased by leakages, which, however, does not lead to a
readjustment of the control slide 54 because, in the static state,
a pressure equilibrium prevails in both the first pressure chamber
70 and in the second pressure chamber 72, but for adjusting
purposes, frictional forces would need to be overcome.
According to the present invention, this is utilized to control the
coolant pump so that during a cut-off of the internal combustion
engine, the magnetic valve 74 is switched so that the control slide
54 is in a respective optimum initial position for the following
starting process. This is in particular performed depending on the
prevailing coolant temperature as compared with a defined threshold
value which corresponds to the normal operation temperature of the
internal combustion engine of approximately 95.degree. C., for
example.
For example, if the ignition of the internal combustion engine is
cut off and the temperature of the coolant is 96.degree. C., thus
exceeding the threshold value, no current is applied to the
magnetic valve 74, whereby the pressure in the second pressure
chamber 72 increases and the control slide 54 is moved into its
position for opening the annular gap 58. As a result, in the case
of a switched-off internal combustion engine, the coolant continues
to circulate due to the thermosiphon effect and thus continues to
absorb heat of the still hot internal combustion engine. The
reverse action can, however, be taken for this cut-off process and
the control slide 54 can be moved into a position to close the
annular gap 58 by applying current to the magnetic valve 74. A
cooling process occurs as a result during a long standstill, but
the heat is stored a little longer. During a following start, the
control slide 54 would be in its closing position so that a rapid
reheating of the coolant for shortening the warm-up phase would
occur. Whether the control slide 54 is moved into its open or
closed position when the ignition is cut off can be decided
depending on the external temperature. At particularly high
temperatures, the control slide 54 would rather be moved into the
open state to provide adequate heat dissipation and thus prevent an
overheating of the engine.
A corresponding control can also be performed for vehicles having
an automatic start-stop system. If the engine is cut off during the
start-stop operation, the control slide 54 should be moved into the
position for opening the annular gap 58 depending on the prevailing
coolant temperature when the operating temperature has been reached
and the threshold value is thus exceeded since only short
standstill periods are assumed during which a major cooling is not
expected but the coolant may be overheated by the warm engine. In
the cut-off state, a circulation is accordingly caused by the
thermosiphon effect. During the start of the internal combustion
engine, the control slide is then in this position so that a
maximum coolant flow can be delivered without any delay. If the
operating temperature has not yet been reached, the control slide
54 is kept in the position for closing the annular gap 58 or moved
into this position during the switch-off process. A circulation of
the coolant is thus prevented, and the engine can transfer its heat
to the stagnant coolant. During a new start, the stagnant coolant
is further heated so that the warm-up phase is shortened. The
control slide 54 is subsequently merely slowly opened to prevent a
surge of cold coolant from flowing from the pump into the
crankcase.
A corresponding control should also be performed in the coasting
mode of the motor vehicle during which the internal combustion
engine is decoupled from the power train and is switched off. After
the switch-off of the internal combustion engine, the current feed
to the valve 74 can subsequently be terminated without the control
slide 54 being moved when the engine is switched off. After a new
start of the engine, the control slide is controlled as required.
This subsequent control can either be performed via a closed
control loop with a position feedback of the control slide or can
be carried out without a sensor system.
Such a method allows for a control of the coolant flow within
physical limits when the vehicle is cut off and allows for an
optimum positioning of the control slide, and thus an optimum
coolant flow, immediately during the starting process of the
vehicle, whereby the cold running phase can be shortened. The
existing heat quantities can be better utilized on the whole, while
overheating is reliably avoided in all operating conditions.
It should be appreciated that the scope of protection of the
present invention is not limited to the described exemplary
embodiment. Other coolant pumps can in particular be used, wherein
it is merely important that the control slide not be moved by
external forces after the switch-off process. Various switch points
for controlling purposes can also be selected or intermediate
positions of the slide can be approached if reasonable. Reference
should also be had to the appended claims.
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